When doing calculations in engineering, many of the variables that we deal with are not constants. For example, if we were to calibrate a digital altimeter to collect accurate altitude position, we need the atmospheric pressure at sea level. It would be nice if pressure stay the same, then we could just hard code that number in. Unfortunately, that is not the case. Pressure changes constantly due to a number of factors.
Because of the continuously changing nature of some of the variable we deal with, this present us with a challenge in engineering. How are we supposed to design the aircraft if conditions are keep on changing?
Well, that’s when the Standard Atmosphere come into play. In simplest terms, the Standard Atmosphere is pretty much just a model that engineers and scientists came up with that generally describe what the average conditions are like. Continue reading →
Aerospace Engineering Units
Before we move on any further, it is probably important to talk about some customs of the aerospace world. In the aviation world, travel distance are measured in nautical miles and speed is measured in knots. 1 nautical mile (nm) = 1.15 miles and 1 knot = 1.15 mph. This system is developed such at 1 degree of Earth’s longitudinal length is equals to 60 nautical miles. For space, we sometime use AU, Astronautical Unit, 149.6E9 m, distance between Earth and Sun. In engineering, we generally use Imperial system for aviation and Metric for space. But both works and I prefer metric. Remember the standard units when calculating: use seconds for time, meter or feet for distance, m/s or fps for speed (60 mph = 88 fps), kg or slugs for mass, Newtons or pounds for force, Kelvins (+273.15 C) or Rankine (+459.67 F) for absolute temperature.
Fundamental Forces of Flight
In aeronautics, there are four fundamental forces that act upon the aircraft during inner-atmospheric flight. The four forces are:lift, weight, thrust and drag. The picture below show a graphical representation of the forces.
*NOTE: these four forces only apply within a planet’s atmosphere, there is de facto no lift, weight or drag in space due to the absent of a working fluid and the insufficient amount of gravity. Not to say there’s no gravity in empty space, but it is just not enough to make a rocket go down like how it would near a planet. Continue reading →
In this section, we are going to go over the basic parts of an aircraft and their basic functions. We are also going to discuss the four fundamental forces in flight and also the parameters that affect flight conditions.
It is probably a good idea to first learn about the history of Aerospace Engineering. What is it that make this discipline of engineering so special? Why is it so expensive? If you have ever looked into Wikipedia, you will probably found that aerospace engineering is actually spitted into two major sub-disciplines. They are aeronautics and astronautics. Continue reading →
Before beginning the first section of Introduction to Aerospace Engineering, I would like to start by thanking Professor Terry Hart of Lehigh University for being such a great teacher that make engineering class fun and interesting again. His stories of flying fighter jets in the Air Force and the Space Shuttle with NASA is just fascinating and kept me going in this very difficult Junior Spring semester. I really like the way how he have equation sheets and notes all prepared for student to open up and learn. Hoepfully I don’t do too bad of a job trying to recite what I learned here, lol.
While I was a still a young boy, I parents used to bring me to Hong Kong Kai Tak Airport all the time to watch the planes takes off and lands. Not only that, I also got to fly on them often, sometimes just to the Southeast Asian countries, sometimes across the globe. They also brought me to the Hong Kong Science & Space Museum all the time (free admission on Wednesday…), and along with watching Apollo 13, yeah, I was determined to become an Aerospace Engineer and hopefully one day get to fly myself into the sky or even to space! Well… that last part probably wouldn’t happen, xD. Continue reading →